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PostPosted: Mon Nov 02, 2015 6:17 pm 
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Mahogany
Mahogany

Joined: Mon Sep 22, 2008 6:27 pm
Posts: 44
Does anyone have any experience laminating top and back plates for resonator. I am contemplating laminating solid Mahogany a little less than 1/8" to baltic birch ply also 1/8". Would there be expansion problems? It would of course be well braced by back braces and top ply ledge for cone.


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PostPosted: Wed Nov 04, 2015 4:32 pm 
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Koa
Koa

Joined: Fri Jan 25, 2008 9:55 am
Posts: 919
Location: Traverse City Michigan
Not sure. Seems odd. 1/8 is thick enough by itself. Not sure how stiff you need it. I would think better to go three ply. 1/16 -1/16 cross- 1/16.


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PostPosted: Thu Nov 05, 2015 11:28 am 
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Koa
Koa

Joined: Thu Nov 04, 2010 1:46 pm
Posts: 868
First name: Freeman
Last Name: Keller
Focus: Build
Status: Amateur
My 1932 Dobro is birch plywood approximately 1/8 inch thick with the only "bracing" being the soundwell (which does extend from top to back) and neck stick. I have built resonators out of non-laminated timber - in my case 1/8 thick koa with normal ladder back bracing and the soundwell on the top.

Image

fwiw - the tricone used a standard bolt on neck instead of a neck stick and has held up fine. I see no problems in laminating the woods but I also see no advantage.


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PostPosted: Thu Nov 19, 2015 7:06 pm 
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Mahogany
Mahogany

Joined: Mon Sep 22, 2008 6:27 pm
Posts: 44
Thanks for response guys. I have since had the chance to look new El Trovador over pretty closely and the top was a ply looking about 3/16".
The top veneer looked about 3/64" Mah. The sides are solid Mah, and a ply back, though they make it with solid back as well. Round necked.
I am thinking of laminating a jointed top of mahogany 1/8" or so thk. onto a 1/8" baltic birch, and then thickness sanding to a hair over 3/16".

I am reproducing the El Trovador, because I love the sound I have heard from Mike Dowling's repro. I am doing this without plans. Purchasing the cone and biscuit from National. I want to bolt on the neck, but am still unsure about the neck angle. The top is tapered toward the neck slightly from just in front of the reso plate. Once i get the cone, I will use it to do a side view drawing. The thing I am uncertain about is what happens to the whole thing once pressure is placed on when strung up. The cone goes down, but by how much? questions questions questions. Appreciate any help you can be. The web is a neat thing when used right.. BTW is the fingerboard extension typically glued on to the top as with regular acoustics, They seem to use 5 fasteners thru the FB and covered with plugs.


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PostPosted: Sun Nov 29, 2015 9:58 pm 
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Koa
Koa

Joined: Thu Nov 04, 2010 1:46 pm
Posts: 868
First name: Freeman
Last Name: Keller
Focus: Build
Status: Amateur
FR, I have the old Resophonic Outfitters plans for a metal bodied biscuit guitar, as well as a 1980 Dobro Duolian (plus the Type 27 and tricone mentioned above). The plans show the neck angle at 1/2 degree but they don't really say what that is referenced to. The top of the saddle on their plans is 11/16 over the plane of the guitar top at the sound well. If I strike a line from the top of the frets to the biscuit, the saddle is 6/16 above that line.

Next, when I strike a line from the top of the nut to the top of the saddle I get an action at the 12th fret of 7/32. Note that I did not calculate either nut or saddle slots - obviously that will take it down a little, as will loading the cone with string tension. One caution here, a friend borrowed my Duolian and tuned it up to open A, and crushed the cone. Either plan to tune down or run really light gauge strings (I use mediums)

Usually the sound well on a biscuit is one inch deep. Most of them have neck sticks which allows the neck to be angled - that is how you adjust the action on any resonator. You can do the same thing with a bolt on neck - just set the neck until you get the string plane where you want it for your preferred action. Most resonators do not have the f/b extension glued to the top, instead there are two or four wood screws holding the extension to the top - they are covered by pearl dots on the f/b.

You have limited adjustment of the action by the depth of your saddle slots but not very much. You will also have to decide how much radius to put into your neck (depends a lot on your playing style) which then gets transferred to the saddle. Last decision on setup is whether to put any compensation into the scale lengths - most resos have none and play terribly sharp when fretted. I chose to add about 1/16 to the tricone - equal on both sides. The reason I say all of this is that unlike an normal acoustic, with a reso everything starts at the saddle which becomes fixed when you make the sound well.

Here is a picture of my Duolian showing the neckstick and supporting "mushrooms"

Image

String tension does slightly load the cone but I really don't think it depresses much. You will want to do the final setup with the cover plate off

Image


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PostPosted: Tue Dec 29, 2015 5:31 pm 
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Mahogany
Mahogany

Joined: Mon Sep 22, 2008 6:27 pm
Posts: 44
Well I am about to start this project. Building with a friend to keep me at it. He has never built, so it is a pleasure to offer him this opportunity. We built two molds and a bender. Will be making a side profile template tomorrow. I only have 12' and 25' radius bowls, so I am going to use the 25' for the back. The top is essentially flat with a taper to the headlock of 2 degrees starting just ahead of the sound well. The top will be laminated and the back and sides solid, African Mahogany. Scored a lovely piece of Peruvian Walnut for the necks.

Thank you Freeman Keller for your good info. So here goes. Happy New Year to each and all!!


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PostPosted: Wed Dec 30, 2015 11:32 am 
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Koa
Koa

Joined: Fri Aug 19, 2005 4:02 am
Posts: 1701
Location: United States
The woodworking rule in making laminations is to treat both sides equally. If you laminate a veneer on the show side then you better do the same for the back. Otherwise you will have warping of the panel.



These users thanked the author Barry Daniels for the post: frwilliams (Tue Mar 29, 2016 7:59 am)
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